When installing carpet into a room a tack strip is used to secure the edges of the carpet along the walls. When installing carpet, one edge of the carpet is secured onto the tack strip which extends along the bottom edge of one wall of the room. The carpet is then stretched by stretchers and secured onto the tack strip which has been positioned along the floor next to the walls on the opposite side of the room. The process of installing carpet is similar to stretching the drum skin over a drum. The stretched carpet is held in the final position by the tack strip which extends along the perimeter of the room.
The tack strip is made from strips of plywood, typically 4 or 5 ply plywood, which are at least a ¼ inch thick. A number of tacks are inserted in the plywood in order to hold a carpet backing. Nails are inserted in an opposite orientation from the tacks. The nails then may be nailed into the flooring. The tacks then extend from the tack strip (pointing towards the ceiling) allowing the carpet to be secured to the tack strip. The combination of the tack extruding from the face and the nails holding the strip to the floor is highly effective for holding a carpet in position.
The tack strip may be made in a variety of widths. A variable number of rows of protruding tacks may be used to secure a carpet but at least two rows of protruding tacks is preferred. The tack strip is typically made in a ¾ inch width with tacks in two rows spaced approximately ½ inch apart. The tacks are inserted in an alternating manner, roughly 1 tack every ¾ inch so as to not crack the strip of plywood into the which the tacks are inserted. The tack strip may be made in wider widths such as 1¾ inch in order to allow an extra row of alternating tacks to be inserted in the tack strip. This extra row of tacks is required when the tack strip is used to secure carpet in large rooms. In large rooms the force generated by stretching the carpet into a sufficiently tight position is greater requiring additional tacks to secure the carpet in place.
The tack strip is generally made in lengths of 4 to 5 feet. When laying lengths of tack strip in an area where the carpet is to be installed the carpet installer will often encounter areas where they cannot apply a complete 4 to 5 foot length of tack strip. The installer is required to cut the full length of the tack strip down to a length that will fit in a particular area. This is especially true around doors or irregularly shaped fixtures within a room. Cutting tack strip in a precise manner is very difficult to be done by hand simply by snapping the tack strip. The material is too thick to easily snap by bending and the tacks and nail combination make it difficult to grasp the tack strip. A tool is needed to cut the tack strip to the precise length required.
Although it is possible to cut the tack strip with an axe, this does not allow precision cutting. Precision cutting is needed in corner areas where mitering at a 45° angle is desirable. Use of an axe is also likely to smash down or blunt the sharp tacks of the tack strip. A greater precision is desirable.
A number of tack strip cutters are commercially available. For example, U.S. Pat. No. 3,790,976 to Stencil discloses a device for cutting tack strips including a lower blade holder and an upper blade holder joined at a rear pivot. A handle connects the lower blade holder and upper blade holder. When the handle is depressed the blades held on each holder move together a tack strip to be cut at a precise location.
The tack strip cutter may use replaceable blades. The handle provides a leveraged force providing a downward vertical force which is able to cut through the plywood tack strip. This device also includes a foot at a rear position distal from the two blades on the blade holders. The foot is designed so that it can be positioned on a floor to stabilize the tool during cutting. The handle provides leverage moving the top blade holder towards the bottom blade holder with sufficient force to cut the tack strip across a precise line with relatively little effort. This pressure allows the tack strip to be cut across a precise line using relatively little force.
Such a device may be spring loaded. A spring loaded device is able to open automatically following cutting the tack strip. The razor blades are replaceable and extra blades may be stored in a compartment on the device.
The tool is used a number of times in installation of carpet even in average size homes. As homes are built with increasingly open plans having large rooms, the use of 5-ply or greater tack strips and 1¾ inch wide tack strips are more common. To cut through these wider tack strips requires the use of longer replaceable blades. The blades also must be taller to allow for cutting through material that is increasingly thick. In addition greater leverage forces are needed.
After repeated use, the blades begin to dull, and a number of problems develop. Dull blades resist cutting into the plywood causing one or both blade carriers to deflect longitudinally away from each other. This has a number of effects. First it diminishes the downward force of the blades since some of this force is now going to be channeled to moving the blades to the side. This increases the pressure required to cut through the strip. Secondly, as the blades deflect away from each other a gap between the blades widens. When this gap is sufficiently wide a thin strip of wood is cut by the two blades and may be stuck between the blades after the tack strip has been cut. This thin fragment of wood often becomes wedged between the blades. This prevents the spring-loaded handle from opening automatically because the blades are pinned in place by the wood fragment. The user must jar this fragment from between the blades. This is done by striking the tool on the surface to pry open the jaws. Alternatively, a user could pry out the fragment manually. However, such manual removal of the thin wood fragment from between the blades exposes the user's fingers to possible injury from the blades.
To prevent the fragments from sticking between the blades, the user may decide to frequently change the blades. However blades are costly and changing the blades takes time. An improved cutter that can reduce the deflection of the blades could allow the blade life to be extended, thereby reducing costs. It is an object of the invention to provide a tack strip cutter in which the longitudinal deflection of the blades is minimized.